The life-history of Contarinia nasturtii (Kieff.), a gall-forming pest of swedes, was investigated in northern England in 1958–60, particular attention being paid to the influence of temperature and moisture on development in the soil. Most of the observations were made under controlled conditions in the laboratory, although much of the material came from the field.The adults emerge from the soil, mate, and live 1–3 days. In laboratory conditions, each female developed about 95 eggs, laid in batches of 2–50 on the young leaves of the host plant, and produced 78·7±11·4 unisexual larval progeny. The eggs require moist conditions, and hatched according to temperature after 1–10 days at 30–10°C. The larvae fed for 7–21 days at 25–15°C., producing a gall.The full-grown larvae burrow into the soil. It was found that they either pupated in oval-shaped cocoons just below the surface, producing adults 10–48 days later (at 25–12°C.) or become dormant in spherical cocoons. At 32·5°C. the pupae died, and below 32·5°C. males developed faster than females by about 24 hours.Dormancy is caused either by diapause, in which case the larvae require prolonged chilling before development can be resumed, or by drought, in which case development is resumed immediately in response to wetting.The incidence of diapause increased regularly during the summer generations, probably in response to decreasing day-length, and the larvae tended to avoid diapause when placed in high temperatures (e.g., 25°C.). The firmness of diapause appeared to vary according to the conditions experienced by the feeding and full-grown larvae, but, in general, the larvae completed diapause development after 100 days at 2–5°C. followed by 30 days at 20–25°C., i.e., after exposure to conditions similar to those experienced by the diapause larvae during winter and spring.Dormancy due to drought (quiescence) affected both non-diapause and post-diapause larvae; the former became quiescent on entering dry soil (pF>3·5–4·0), and the latter remained inactive if kept in dry or even in moist soil (pF 3·4) after completing diapause. In both cases, the termination of dormancy occurred immediately in response to a thorough wetting of the soil. The larvae left their spherical cocoons, moved to the surface, re-entered the ground and pupated in oval cocoons as if entering the soil for the first time.Factors that delay pupation of C. nasturtii similarly delay the development of its Hymenopterous parasites and hence synchronise the emergence of the adult parasites with the host's feeding stage.

An entomological radar was used to observe insect flight activity at a coastal locality in north-western Tasmania during the spring of 1973. Insects were regularly observed to take off at dusk, and local movements from nearby islands were detected on several occasions. Large-scale southward movements of insects across Bass Strait were also observed and were found to be associated with the warm anticyclonic airflows which occur ahead of a cold front. Light-trap catches indicated that the insects were noctuid moths, with Persectania ewingii (Westw.), Heliothis punctiger

The paper attempts to explain the causes of phasmatid outbreaks in a theory of outbreak release which is based on direct observations of the phasmatid Didymuria violescens (Leach) and a subjective analysis of several outstanding features associated with the history, distribution, and development of phasmatid outbreaks in the highlands of south-eastern Australia. The outbreaks of D. violescens are largely confined to mountain forests in southern New South Wales and Victoria where a 2-yr generation period predominates and a 2-yr cycling of population prevails with peaks and troughs of hatching, and hence "peak" and "off" years of phasmatid abundance, in alternate years. Birds greatly limit the survival rate of D. violescens during off-years but are ineffective during peak years because of their limited total response to increase in numbers of the prey. The theory implies that D. violescens has two systems of control: one at low density when increase is limited largely by egg parasites or birds or both; and another at high density when increase is ultimately prevented by intraspecific competition for food. The theory postulates that very cool summer weather conditions may occasionally disrupt the low-density system of control and thereby initiate outbreak release either directly in some situations or indirectly in others.

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